Category Archives: In Situ Observations

A tale of two drifters

We have recovered all of our (SIO, Feddersen) instruments, and the fun of sorting out and QCing the data has begun, however, I thought I’d share a sweet tale of loss and love. We were fortunate to only leave 2 instruments at Pt Sal, drifter 23 and 24, although I do believe their fate may have always been intertwined. Their tale begins during experiment preparation during final drifter assembly, when drifters were being labeled with a sharpie: 1… 27 – then 23 and 24 were shipped to Pt Sal, right next to each other in a large box. During IOP-1, both 23 and 24 rose to the occasion and provided excellent data from which internal waves, fronts, and surface waves were observed. However, on the final day of IOP-1, Sept. 17, drifter 23 (red in the figure) decided he/she wasn’t long for this world and sacrificed itself (for science, I presume) on the rocks, either that or that the point (0,0) in Pt Sal (x,y) is some sort of worm hole? (actually, we checked some mooring lines, which were kelp free! delaying recovery of 23). Regardless, we had finally lost a drifter, much to everyones dismay (delight?).

Now drifter 24 was sad, however, he/she performed admirably throughout IOP-2 collecting much data. On the final day of IOP-2 (Oct. 14), about 1 month after losing drifter 23, 24 decided enough was enough and attempted to reunite with 23. Upon release at 8:05, 24 went directly shoreward (green in figure), hitting the surfzone at 12:39. Realizing that 23 was 1 km to the south, 24 stumbled down the beach for 4 hours, getting about 200 m from 23’s final resting place. At this point, after stumbling down the beach for 4 hours (a difficult task for an old drifter from the 80s), 24 needed a rest. After a long 24 hour nap, drifter 24 made tje final push south toward 23, coming to rest about 100 m from his partner in science. Although we mourn the loss of these two drifters, we are happy they are once again together enjoying their retirement on a beautiful coastline. (in the figure, contours are at 2.5 m intervals, and the 20 m contour is thick)

 

An Oceano trifecta in X-band vision

The IOP1 asset visualization now includes 3 ships, 3 boats, 2 sets of drifters and x-band radar images! Thanks to Falk Feddersen for hosting the full video of IOP1!

On 15 September the UNOLS vessel trifecta encountered mingling fronts and internal wave packets headed onshore during Oceano surveys. Two-hours of near-surface temperature data trail each vessel. The tightly-packed moorings, soon to be recovered, were in the middle of it all.  Good luck to the mooring recovery teams!

IOP2 fun around Pt Sal

SIO-Whaler Sally Ann on her offshore (west) survey leg passing to the south of Ghost Reef on 10 October. Photo was take by Falk Feddersen from the RV Sounder

 

IOP2 has been a great deal of fun all around sampling both Pt Sal and Oceano with the Sounder, Kalipi and Oceanus.  Speaking of Oceanus, On 14 Oct, Mike Kovatch took some cool photos on of her from east of Pt Sal looking between Lion Rock on the left and Pt Sal on the right as the Oceanus was doing her onshore leg  and making the turn. 

 

We had three great days at Pt Sal and below are some plot of both the first day (9 Oct) and the last day (14 Oct).    On 9 October, Sally Ann and Sounder repeated the survey lines they did for the first IOP.  Survey lines and CTD data is shown beow.  Lots of repeatable frontal structure.

 

What might that frontal structure look like from the surface?  Well it looks like foam scum lines that are filled with algae. The two photos below are from 9 October which had Hs>2 m.   The first photo is looking north at Pt Sal and Lion Rock.  Note the big foam/algae streak (scum line) heading from Pt Sal to the right of Lion Rock.   The scum line can be very dense – even a few inches thick of foam!

Algae scum line coming off of Pt Sal and heading SE indicating the presence of a front where downwelling is occuring.

Close up of massive algae scum line coming off of Pt Sal on 9 October.

 

On IOP2 Day 6, 14 October, we again had 4 vessels doing joint surveys with the APL plane flying IR & visible and helping guide us.  The Sally Ann did a survey box much tighter near the strong bathymetric variations around Pt Sal.    The survey box below started east just offshore and south of Ghost Reef, passed Seal Rock and then Lion Rock, before turning north for a short leg and then offshore again between Pt Sal and Lion/Seal Rocks.

Here are some photos of those features.

A wave breaking at Ghost Reef up close on 15 Oct. The depth goes from 15 m to <4 m very rapidly (Mike Kovatch).

The NPS boat “SandCrab” racing to the south past Ghost reef to recover instruments. They did not stop for tea and biscuits (Mike Kovatch)

Waves breaking on Seal Rock just south of Pt Sal. Drifters recirculated behind this feature (F Feddersen)

All boats passed through many strong frontal features that had more wake, eddy, and recirculation properties than of NLIW.   Notice the repeatable front properties as the Sally Ann drove the box 4 times.

Sun sets on turnaround cruise

The R/V Oceanus offloaded personnel early this morning in Monterey Bay, bringing to a close the ship’s role in the second intensive operating period (IOP). The Oceanus weathered some sizable swells this past week and is currently steaming up to Newport with hopes of dodging another incoming storm in the north. This research vessel never sleeps.

To commemorate the hustle and bustle we have seen aboard these last twelve days, here is a science GIF (the best type of GIF, if you ask me!) from October 6th.

Mooring redeployment at dusk on October 6th aboard the R/V Oceanus

This sequence is from redeploying our second mooring (MS50-T). You can see us standing in a line on the deck of the ship, holding instruments in hand as we wait for the top float to be released overboard.

I have to admit that the feeling of putting those first few moorings back in the water– after an exciting and frenzied 24 hours between recovery and redeployment– was that of pride and relief: pride for how much we had accomplished in a short amount of time, and relief that the instruments were going back into the ocean where they belonged. As engineer Pavan Vutukur said when he saw the mooring returned to the water with numerous of his lab’s GusT instruments attached:

“Now that they’re going back? I feel so much better.”

We look forward to seeing those instruments again at the end of October. But for now, the sun has set on the second IOP aboard the Oceanus.

— Jenessa Duncombe and the R/V Oceanus team

The R/V Oceanus sets sail once again

The crew on the R/V Oceanus left port today from San Francisco under a fortuitous blue sky. We are headed south to Point Sal and expect to arrive in the morning on Thursday. We plan to recover and re-deploy up to 8 moorings and 9 landers over the next five days, as well as continue surveys with the towed Mini-bat/Acrobat (fingers crossed that the kelp forests stay out of our way this time). We have a new instrument as well— a bow chain equipped with thermistors and two GusT’s (pressure readers for depth and turbulence).

Our departure marks the beginning of turnarounds for the long-term moorings and we are excited to get our hands on the data. We do not know what we will find when we make it to the first station tomorrow. Has our mooring “walked” away from its original location? Has any fishing activity inadvertently interacted with our surface buoy? Or is our mooring and its all parts bobbing where we left it last, instruments dutifully recording data?

We hope the last option, but we are prepared for whatever we find. We have fresh batteries and all hands on deck for the recoveries.

Speaking of the team, we have some new faces aboard. The group hails from Oregon State University, Scripps Institution of Oceanography, and the University of Miami. We have five research scientists, two graduate students, two technicians, one postdoc, one engineer, and lastly, one volunteer scientist/journalist (that’s me!). We also feel grateful for our MarTech and Oceanus crew.

Here are a few photos of our time on land, as well of us exiting the bay under the illustrious Golden Gate bridge.

Stay tuned to hear about mooring and landing recoveries.

— Jenessa Duncombe and the R/V Oceanus team

R/V Oceanus at sunrise with the San Francisco skyline in background

Engineer Sara Goheen readies the bowchain

Engineer Pavan Vutukur and Technician Marnie Jo Zirbel service the mini-bat instrument

The science team

scripps oceanography uc san diego